基于全相位快速傅里叶变换谱分析的激光动态目标实时测距系统

Real-Time Laser Range Finding System for Moving Target Based on All-Phase Fourier Transfrorm Spectrum Analysis

针对传统的激光测距仪测量速度慢、抗干扰能力低以及实时性差等问题,提出了基于并行数字信号处理器(DSP)的多通道发射和接收的测距系统。在系统中实现了多个调制频率激光的同时发射和同时接收,压缩了测量时间,避免了因目标运动造成的测量数据无法正确融合的问题;根据全相位快速傅里叶变换(FFT)获得的频谱信息,提出了一种将信号幅度谱按泰勒级数展开以求取频率泄露值进行频谱校正的方法。蒙特卡罗(Monte-Carlo)仿真实验证明,该方法较双谱线(Rife)法和能量重心法有较高的精度和良好的稳定性。系统中,AD转换器采样频率为937.5 kHz、进行全相位FFT变换的点数1024时,相位测量精度为0.003°,频率测量精度为0.033 Hz。实验证明,该系统能满足相位法测距系统对实时动态目标测距的需要。

The traditional laser range finder cannot meet the need of real-time,high-resolution measurement because of its low anti-jamming capability and time-consuming measurement.Owing to this,multi-channel transmitting and receiving system for phase-shift laser range finder based on parallel digital signal processor（DSP） was designed.Multi-frequency modulation laser can be transmitted and received at the same time,whish improves the measurement speed and avoids the wrong data fusion because of target moving.A new frequency correction method was proposed according to the amplitude spectrum acquired by all-phase FFT,amplitude spectrum is expanded into Taylor series and the correction value of frequency is calculated by relation of spectral lines.Monte-Carlo simulation results proved that the new frequency correction method had higher resolution and better stability than Rife method and centro-baric method.In experiments,the sampling frequency of AD converter is 937.5 kHz,the all-phase FFT transform point number is 1024,the phase difference resolution better than 0.003° and the frequency resolution better than 0.033 Hz are obtained.Experiments proved that the system can meet the need of high-accuracy,real-time distance measurement of moving target.